ß-Sitosterol mitigates hepatocyte apoptosis by inhibiting endoplasmic reticulum stress in thioacetamide-induced hepatic injury in γ-irradiated rats.

The endoplasmic reticulum (ER) controls many biological functions besides maintaining the function of liver cells. Various studies reported the role of the ER stress and UPR signaling pathway in various liver diseases via triggering hepatocytes apoptosis. This study aims to investigate the suppressive effect of ß-sitosterol (ßS) on apoptosis associated with liver injury and ER stress. METHODS: Liver damage in rats was induced by TAA (150 mg/kg I.P twice a week/3 weeks) and γ-irradiation (single dose 3.5 Gy) and treated with ßS (20 mg/kg daily for 30 days). Serum aminotransferase activity, lipid profile and lipid metabolic factors were measured beside liver oxidative stress and inflammatory markers. Moreover, the hepatic expression of ER stress markers (inositol-requiring enzyme 1 alpha (IRE1α), X-box-binding protein 1 (XBP1) and CCAAT/enhancer binding protein homologous protein (CHOP) and apoptotic markers were detected together with histopathological examination. RESULTS: ßS diminished the aminotransferase activity, the oxidative stress markers as well as the inflammatory mediators. Furthermore, ßS lowered the circulating TG and TC and the hepatic lipotoxicity via the suppression of lipogenesis (Srebp-1c) and improved the ß-oxidation (Pparα and Cpt1a) together with the mitochondrial biogenesis (Pgc-1 α). Moreover, the upregulated levels of ER stress markers were reduced upon treatment with ßS, which consequently attenuated hepatic apoptosis. CONCLUSION: ßS relieves hepatic injury, ameliorates mitochondrial biogenesis, and reduces lipotoxicity and apoptosis via inhibition of CHOP and ER stress response.